During endoscopy, i.e. the examination of body cavities by means of an endoscope or a surgical operation employing an endoscope, it often happens that the area being viewed or operation area must be freed of debris in order to obtain a clear field of view or to clean the actual site of the operation. Especially when the material to be removed is very solid or firmly attached to the wall of the body cavity, it is difficult to expose the regions of interest.
Rinsing devices to rinse or clean a region to be treated or operation field are known, by means of which a rinsing fluid can be applied to the region or field to be rinsed or cleaned by passing the fluid at an adjustable flow rate through a rinsing or instrument channel of an endoscope. However, it is a disadvantage of these rinsing devices that in order to remove solid materials or those firmly adhering to the wall of the organ, a large amount of rinsing fluid must be introduced into the body cavity or hollow organ concerned.
The German patent DE 40 00 410 A1 discloses an endoscope comprising a rinsing device that enables application of an air-liquid mixture through an instrument channel of the endoscope.
For this purpose the said rinsing device incorporates a pump aggregate equipped with both a water pump and an air pump, which can be activated simultaneously or in alternation, either automatically or by operating a switch, so that an air-liquid mixture is passed through the instrument channel into the treatment region or onto the operation field. The air and liquid are brought together within the pump aggregate, in a connecting piece, from which the mixture passes through a single, common tube to a bifurcation at the proximal end of the instrument channel, even when both a water pump and an air pump are attached to the connecting piece.
In comparison to the rinsing devices mentioned above, this rinsing device offers the advantage that less water is introduced into the body cavity or into the organ to be treated; however, it is still not sufficiently effective in removing solid materials or those firmly adhering to the organ wall. The degree to which its efficacy can be increased by raising the pressure of the air-liquid mixture is restricted by the limited pressure resistance of the instrument channels of flexible endoscopes.
The object of the invention is to provide an improved cleaning action in a simple manner, with a reduced amount of liquid and the lowest possible pressure.
This object is achieved according to the method and apparatus of the invention.
It is an essential point of the invention that the cleaning liquid is not, continuously applied, as is known from the prior art, but is supplied toward an examining area in a controlled manner providing a series of separate fluid portions each of which is driven at an accelerated rate by a following gas portion. The energy of such a fluid portion is determined to a greater extent by its velocity, and this velocity in turn can be adjusted within a wide range by the gas pressure and the distance over which the individual projectile-like xe2x80x9cslugxe2x80x9d of liquid travels (which is available to a greater extent especially in very long endoscopes). The amount of liquid thus introduced is correspondingly small and, in addition, can therefore be very easily adjusted, because the adjustment is applied to individual (small) amounts of liquid. A further advantage is that the system can operate with a relatively low pressure (high pressure could endanger the patient and exceed the resistance of the working channel of an endoscope), because the energy of the individual liquid slugs increases progressively over the (long) travel distance, until at the exit opening (in some cases the opening of the endoscope channel) it has substantially reached its maximum.
Preferably a plurality of liquid slugs are ejected in succession, in particular at regular intervals; the pauses between the slugs should not be too short, in order to operate with minimal amounts of fluid and to enable the cleaning process to be stopped immediately, as soon as the desired result has been achieved. It is preferable in this regard for the amount of liquid in each slug (projectile), the pressure of the gas that accelerates the slug, and the intervals at which the slugs leave the opening of the tube all to be adjustable.
In a preferred embodiment of the invention controllable valves are provided, by means of which the tube can be connected in alternation with a source of liquid and a source of compressed gas. This arrangement optimizes controllability. In a particularly simple embodiment of the invention the proximal section of the tube is connected to a liquid source that is under a first pressure by way of a valve that permits flow only in the direction toward the opening of the tube, and is also connected to a compressed-gas source, the pressure of which alternates in time between levels above and below the first pressure. As a result, whenever the gas pressure falls below the liquid pressure, a slug of liquid enters the tube, and when the gas pressure again rises above the liquid pressure, the slug is accelerated and ejected.